proper Red Algae are parasitic, and the view here taken is
t hat in the Disk Lichens we have a group of plants in which
the parasitism has gone further, and has resulted in so
great a modification of the plant body as to place them in
another phylum.
338. The Disk Lichens abound almost everywhere —
on tree-trunks, rocks, old roofs, and in many regions upon
the ground. They are for the most part of a greenish-
gray color, and hence are often called ''Gray Mosses.''
Other colors, as black, purple, yellow, and white, are also
common.
339. The plant-body of a Disk Lichen is composed of
jointed, branching, colorless filaments, similar to those in
-TTTTv-r-T-r-r the other fungi, but usually more or less
compacted together into a thallus, or even
a branching stem. They obtain their
nourishment from little green Myxophy-
FiG. 95.— Section ceac oY ChlorophycesB to which the fila-
ments attach themselves parasitically.
These little hosts, which at first live free in water or on
moist surfaces, eventually come to live in the midst
of the moist tissues of the fungus parasite. They
were formerly supposed to be parts of the lichen itself,
and were called "gonidia," an objectionable term which
is still in common use.
340. Disk Lichens are all of rather small size, vary-
ing from a millimeter or so, to 20 or 30 centimeters in
length. For the greater part the plant-body is flattish,
and adherent to the surface upon which it grows, but
DISK LICHENS 215
some species have more or less elongated branching
stems.
341. Lichens propagate by the escape of some of the
algal cells, with attached fungal filaments by means of
eruptive areas C'soredia") on the plant body. When
one of these comes to rest upon a favorable substratum
it grows directly into a lichen plant body like the original.
Asexual spores appear to be wanting.
342. The sexual organs as far as known remind one
of those of the Red Algae. The oogone, which is a spiral
coil of cells, sends up a slender trichogyne to the surface
of the plant body. Fertilization takes place by means of
minute non-ciliated sperms which are
produced in countless numbers in nearby
cavities (spermogones) in the plant body.
The sperms come in contact with the f^j
projecting trichogyne (doubtless aided
by water) and fertilize the oogone, the organs^ orcou^ml.
result of which is the rapid upward
growth of filaments, the enlarged terminal cells of which
become asci. INIingled with the asci are long sterile cells
(paraphyses) for the protection of the asci and ascospores
in the hymenial layer, which forms a more or less disk-
shaped, or cup-shaped fruit. Such open fruits are known
as "apothecia, " in contrast with the closed fruits C'peri-
thecia") of many of the fungi to be taken up later.
343. The ascospores germinate by sending out one or
more tubes which develop directly into the ordinary fila-
ments of the lichen-body. Experiments have shown that
these filaments will not grow for any great length of time
unless they come into contact with green algae of the
proper species, to which they become attached, growing
rapidly and surrounding them. On the other hand, in
the moist tissues thus formed the green algae find protec-
216 PHYLUM VII. CARPOMYCETEAE
tion and ample opportunity for growing. There is thus
an association between these plants which is mutually
beneficial (symbiosis); the fungus lives parasitically upon
the green algae, to which in return it furnishes
shelter and moisture.
344. Among the Disk Lichens one of the
simplest is the Thread Lichen (Ephebe) found
on wet rocks. In it the fungus filaments
Fig. 97. grow ovcr and around the cells of Scytonema
(parasitic^on or Stigoucma filaments,
cy onema . ^^^^ Some other Disk Lichens are parasitic
upon Nostoc colonies, as in the Jelly Lichens (Collema,
Leptogium), while for the greater part they are parasitic
on species of Protococcus, as is the case with the great
majority of common lichens — Cladonia, Theloschistes,
Physcia, Parmelia, Ramalina, Usnea, etc.
The Cup-fungi (ORDER PEZIZALES)
346. The common Cup-fungus of the woods is a typical
representative of this order. The familiar cup- or saucer-
shaped growth is in reality the spore-fruit C'apothecium"),
while the plant itself is out of sight. The plant consists
of whitish, septate filaments which grow on or in the
ground or in rotten wood, drawing their nourishment from
decaying vegetable matter. These plants are therefore
saprophytes. Some Cup-fungi, however, are known
to be parasites.
347. But little is known as to the asexual reproduction
of the Cup-fungi, but in some species conidia have been
observed.
348. Thesexualorgansof Pyronema("Peziza")are pro-
duced by the sweUing up of the ends of certain of the fila-
ments of the plant into globular or ovoid cells, the oogones,
each having a projection (trichogyne). From below each
CUP FUNGI
217
oogone a slender branch grows out, and becomes the
antherid, which soon comes into contact with the tricho-
gyne. FertiUzation is effected by the passage of the
nuclei from the antherid into the trichogyne and from
thence into the oogone. As a result numerous branches
start out from the oogone,
forming the ascogenous
hyphae. At the same time
their arise numerous sterile
hyphae, from the tissues
beneath the oogone, and
, , 1 • , Fig. 98. — Pcziza, and Pyronema.
these grow upward mter-
mingling with the ascogenous hyphae, forming a dense
felted mass, which gradually takes on the size and form
of the spore fruit. The upper ends of the ascogenous
hyphae become enlarged into asci in which spores
are developed, while the sterile hyphae make up the
remainder of the apothecium, some of them standing
among the asci as the so-called paraphyses. The asci
and paraphyses all reach the same height, and make up
the inner surface of the cup (the ''hymenium"). Upon
escaping from the asci, the spores germinate and produce
the filamentous plants.
The Morels (ORDER HELVELLALES)
349. Morels are related to the Cup-
fungi, and like them are filamentous sapro-
phytes living in the ground. The conical
fruit is stalked, and its upper surface is
studded with hymenial areas in which are
asci and paraphyses similar to those of
the preceding order. A common species
is Morchella esculenia, in which the whitish fruit is
218
PHYLU.M VII. CARPOMYCETEAE
poc
Fig. 100.
Exoascus.
from 7 to 12 centimeters high. It is edible and bears
the name of Mushroom in the central United States.
350. The Plum-pocket fungus (Exoascus), which dis-
torts the young plums in spring and early
summer, is a greatlj^ reduced parasitic sac
fungus (Order Exoascales). Here the plant
consists of delicate threads which penetrate
the tissues of the plum, eventually producing
on the surface poorly developed asci which are
not aggregated into cups.
351. Two additional orders of Hchens — the Slit Lichens
(Graphidalcs) and Closed Lichens (Pyrenolichenes) are
abundantly represented by species of Arthonia, Graphis,
and Endocarpon. In the first order the apothecia are so
nearly closed as to leave only a narrow slit, and in the
second the asci are w^holly enclosed, the fruits being peri-
thecia, with only a minute pore or none at all.
352. The Slit-fungi (Order Hysteriales), are to be
associated with the Slit Lichens, and may be illustrated
by the Black Slit-fungus (Hystero-
graphium) whose saprophj^tic fila-
ments ramify through bark or old
wood and eventually produce small,
black, narrow, elongated, sessile
apothecia, whose edges approximate,
leaving only a narrow slit. Each
ascus contains eight muriform,
elongated spores, and the asci are intermixed with
branched paraphyses.
Fig. 101. — Ilysterogra-
phium.
The Closed Fungi (ORDER PYRENOMYCETALES)
353. The plants of this order are parasitic or saprophy-
tic filaments, and their spore-fruits, which are simple or
compound, are usually hard and somewhat coriaceous.
BLACK KNOT 219
354. A good illustration of the plants of this order is
the Black Knot {Plowrighiia morbosa), which attacks the
plum and eherr}^ In the spring the parasitic filaments,
which the previous year penetrated the 3'oung bark,
multiply greatly, and finally ])reak through the ])ark,
and form a dense tissue. The knot-like mass grows
rapidly, and when full-sized is usually from 2 or 3 to 10 or
15 centimeters long, and from 1 to 3 centimeters in
thickness; it is solid and but slightl}^ yielding, and is
composed of filaments intermingled with an abnormal
development of the bark-tissues of the host-plant.
355. The knot at this time is dark-colored, and has a
velvety appearance, which is due to the
fact that its surface is covered with
myriads of short, jointed, vertical fila-
ments, each of which bears one or more
conidia. The conidia, which fall off
readily, are produced until the latter part
of summer, when the filaments which
bear them shrivel up and disappear.
356. During the autumn asci are produced, but re-
quire the greater part of winter to come to perfection.
The asci grow in the cavities of minute papillae {peri-
thecia), and are intermingled with slender filaments
(paraphj'ses). Each ascus contains eight spores, which
eventually escai)e through an ai)ical pore. These spores
germinate by sending out a small filament, or sometimes
two.
357. No sexual organs have as yet been observed.
Possibly they exist in the dense tissues of the knot, and
fertilization may occur in the spring or early summer,
but they may have disappeared through the excessive
parasitism of these plants.
358. The parasitic filaments of each year's knot gener-
220 PHYLUM VII. CARPOMYCETEAE
ally penetrate downward some centimeters into the unin-
jured bark, and remain dormant there until the following
spring, when they begin the growth which results in the
production of a new knot, as described above.
359. To this order belongs the Ergot (Claviceps), a
common parasite upon heads of rye, and also many of
the black growths upon the bark and wood of trees.
Many species produce black spots upon living leaves,
wdiile many others occur upon dead leaves and twigs.
360. The Closed Fungi include a large number of
exceedingly injurious species; they often attack and
destroy not only plants, but also insects, upon which
their ravages are sometimes very great.
The Mildews (ORDER PERI SPORI ALES)
361. These plants, which are mainly parasitic, are
composed of branching septate filaments (hyphae) which
form a white or dark web-like film upon the surface of the
leaves and stems of their hosts. There are both sexual
and asexual spores, and of the latter there are in some
cases two or three different kinds, which are produced
earher than those that result from a fertilization.
362. In the Powdery Mildews (Family Erysiphaceae) ^
which are all parasitic, the jointed filaments closely
cover the leaves and other tender parts
of many plants, and draw nourishment
from them by means of suckers (hausto-
ria), w^hich project as irregular out-
growths from the side next to the epi-
^'"'o/Er^Tiphe'^'^ dermis. These suckers apply them-
selves closely to the epidermal cells, and
penetrate them.
363. The crossing and branching filaments soon send
up many vertical branches, which continue to form new
POWDERY MILDEWS 221
cells below by cross partitions. The cells thus formed are
at first oblong and cyhndrical, with flattened ends; but
the topmost ones soon become rounded at their extremi-
ties, thus giving rise to a row of cells, the spores, or
conidia. These fall off successively and germinate at once
by pushing out a tube, which gives rise to a new plant.
364. The sexual process (generation) in most species
takes place late in the season. Two
filaments crossing each other or coming
into close contact swell slightly and send
out from each a short branch; one of
these becomes the oogone, and the other
the antherid, both organs being very fig 104— Gcncm-
much reduced. tion of Erysiphaceae.
365. Fertilization is effected by the direct union of
protoplasm. Eight or ten branches then bud out below
the oogone, and growing upward soon completely enclose
it in a cellular coat which eventually becomes hardened
and turns brownish in color, constituting the spore-fruit
(perithecium).
366. The oogone inside of the perithecium gives rise,
by branching, to one or more large cells (young asci)
filled at first with granular protoplasm, which soon forms
two to eight spores (ascospores) , Upon its outer surface
the spore-fruit develops long filaments (known as
** appendages''), probably for holdfasts. In some genera
these terminate in hooks; in others they are dichotom-
ously branched; in still others, needle-shaped; while in
many species they end irregularly. The spore-fruits re-
main during the winter upon the fallen and decaying
leaves, and finally, by rupturing, permit the asci, with
the contained spores, to escape.
367. The Herbarium-mold (Aspergillus) is related to
the Mildews and belongs to the order of Little Tubers
222 PHYLUM VII. CARPOMYCETEAE
(AspERGiLLALEs). It is commoii on poorly dried speci-
mens in the herbarium, and also on moldy hay and decay-
ing vegetation generally. It sends up vertical branches,
which swell at the top and bear a great number of small
protuberances (the sterigmata) , each of which produces
a chain of conidia.
368. The sexual organs appear a little later than the
conidia. The end of a branch of the plant becomes
coiled into a hollow spiral which con-
stitutes the oogone. From below the
spiral an antherid grows upward, and
brings its apex into contact with the
upper cells of the oogone. After fer-
tilization other branches grow up
Fig. 105.— Aspergillus, arouud the oogouc, and finally com-
pletely enclose it, as in the Mildews,
described above. In the meantime from the cells of the
enclosed oogone branches bud out, and finally produce
many eight-spored asci on their extremities; later the
asci are dissolved, and the spore fruit, now of a sulphur-
yellow color, contains a multitude of loose spores.
369. The Blue Molds (species of Penicillium) are
related to Aspergillus. The conidial stage is a common
Blue Mold on decaying fruit and pastry. The sexual
organs resemble those of the herbarium-mold, and the
spore-fruit is a minute truffle-like body as large as a
coarse sand-grain.
370. Yeast-plants. A still greater degradation of the
sac-fungus type is reached in the minute plants which
occur in yeast. If a bit of yeast be placed upon a glass
slip and carefully examined under high powers of the
microscope, there will he seen very many small roundish
or oval cells, of a pale or whitish color. They have a
cell-wall, but generally the nucleus is indistinct. These
YEAST PLANTS 223
little cells are Yeast-plants, and bear the name of
Saccharomyces cerevisiae.
371. The}' reproduce l^y a kind of fission, called
"budding.'' Eacli cell ]nishes out a little projection
which grows larger and larger, and finally a cell-wall
forms between it and the old cell and these sooncT or
later separate from one another. Under
favorable circumstances certain cells form
spores internally, and these are now re-
garded as asci, homologous with the asci
of the higher sac-fungi. Yeast-plants are,
therefore, to be considered as greatly sim- Fig. iog.— Sac-
plified Sac-fungi, and they are members of ^ ^romyces.
the family Saccharomycetaceae (of the Order Hemi asc ales)
which has experienced what is probably the greatest
reduction suffered by any plants of the Ascosporeae,
372. Yeast-plants are saprophytes, and live upon the
starch of flour. They break up the starch, and in the
process liberate considerable quantities of carbon dioxide
which appears as bubbles upon the surface of the j^east.
Another result of the l^reaking up of the starch is the
formation of alcohol; hence the growth of yeast-plants in
a starchy substance is always accompanied by what is
known as alcoholic fermentation. The housewife and
baker use yeast-plants for the carbon dioxide gas which
they evolve, to give lightness to the bread, while the
brewer and distiller use the same plants for the alcohol
produced b}' their activity. (See Chapter IV, paragraph
139.)
373. The Truffles (Order Tuberales) are well known
from their large underground spore-fruits, which are
edible. Internally there are narrow tortuous channels
on whose walls asci develop, each containing a numl)er of
spores. Little is known of their round of life, and the
224 PHYLUM VII. CARPOMYCETEAE
sexual organs have not been discovered. The part of
the truffle that we eat is the large spore-fruit. These
are collected in Europe by experts and preserved for the
market, where they command high prices.
Laboratory Studies, (a) Collect fruiting specimens of the
common fruticosc lit-hcn (Usnca), which grows upon branches
of trees in forests. Make thin cross-sections of the stem, mount
in alcohol, afterward adding dilute potassium hydrate. Study
the filaments and their relation to the algae. Isolate some of
the algae by tapping on the cover-glass, and note their resem-
blance to Green Shme (Protococcus).
(6) Make thin vertical sections through one of the fruiting
disks, mount as above, and study asci, ascospores and para-
physes.
(c) Collect some of the small, flat, many-lobed hchens which
grow on the bark of apple-, maple-, and oak-trees, and which
have small blackish fruit-disks. Make careful sections of the
plant-body through the fruit-disks, and study the whole struc-
ture, ascospores, asci, paraphyses, filaments, and algae.
(d) Search for cup-shaped fungi, in the spring, about old
hot-beds and upon well-rotted barnyard-refuse. A common
cup fungus of an amber color often to be met with in such
localities is one of the best for the study of ascospores and asci.
Make very thin sections at right angles to the inner surface.
(e) Collect the bright red saucer-shaped cup-fungus {Sar-
coscypha coccinea) growing in the woods upon decaying sticks
and having a diameter of 1 to 4 centimeters. Make similar
sections.
(/) Collect a few Morels {Morchella esculenta), and make
sections at right angles to the surface of the pits which cover
the upper portion and examine for ascospores and asci.
(g) Collect fresh specimens of Plum Pockets, and preserve
them in alcohol. Study the fungus by making very thin
sections at right angles to the surface. Each ascus will be
found to contain several rounded ascospores.
(h) Collect Sht-fungi (Hystcrographium) on the bark of oak
or ash trees, or on dead twigs of sumach, and other shrubs.
The apothecia are black and carbonaceous, and are about a
millimeter long.
LABORATORY STUDIES 225
(i) In early summer examine the choke-cherry and plum
trees (wild and cultivated) for the 3'oung stages of Black Knot.
Watch the development until the knot becomes velvety in
appearance (about midsummer). Now make very thin cross-
sections of the knot and examine for conidia. The several
stages may be readily preserved in alcohol for future study.
(j) Late in autumn and in early winter examine the knots on
the same trees. Note the young perithecia, i.e. hollow paj)illae.
Make very thin vertical sections through some of these. No
perfect ascospores can be found at this time.
(k) Collect fresh knots in midwinter and make similar
examinations, when the asci and ascospores may be found.
(/) In the autumn collect a quantity of leaves of the lilac
which are covered with a whitish mold-like growth, the Lilac-
mildew (Microsphaera alni). Scrape off a bit of this Mildew
after moistening with a drop of alcohol; mount carefully,
adding a httle potassium hydrate. Look for conidia and
haustoria. Look also for spore-fruits, which appear like minute
dark dots to the naked eye. Carefully crush the spore-fruits
and observe the asci (four to seven) with their contained
ascospores (6). Note the beautifully branched tips of the
appendages.
(m) Collect and study the mildews to be found on hops
(Sphaerotheca castagnei), on cherry- and apple-leaves {Podo-
sphaera oxyacanthae) , on hazel- and ironwood-leaves (Phyl-
lactinia suffulta), on willow-leaves {Uncinula salicis), on leaves
and fruit of grapes {U. necator), on wild sunflowers, verbenas,
etc. (Erysiphe cichoraccanun) , on peas, grass, anemones,
buttercups, etc. {E. comynunis).
(n) Place a few shps of green twigs in an ordinary plant-press,
allowing them to remain until they become (1) moldy (conidial
state), and (2) covered with minute yellow globular bodies (the
spore-fruits) . These are known as the Herbarium-mold (.1 spcr-
gillus herhariorum) . Study as in the case of the Mildews.
This can frequently be obtained by placing a piece of almost
dry bread under a bell jar for a few days.
(o) Blue Mold may be obtained from decaying fruit, pas-
try, etc.
(p) Place a minute piece of "compressed" yeast upon a glass
sHde, add a little water, cover with a cover-glass, tapping it
down gently. After a short examination under a high power of
15
226 PHYLUM VII. CARPOMYCETEAE
the microscope add iodine, which will stain the starch-grains
blue or purple, and the yeast-plants j^ellowish. Alany of the
latter will be found in process of budding.
(q) Repeat experiment q on page 103 for production of
carbon dioxide by yeast.
(?') Spread a little ''compressed" yeast on a fresh-cut shce
of potato or carrot; cover with a tumbler or l^ell-jar to kee]:) it
moist; after a few daj^s (four to eight) examine for cells which
are producing ascospores.
(s) Commercial Truffles are natives of Europe, but they may
be obtained for study in our markets. Make thin cross-
sections of the large spore-fruit and examine the ascospores and
asci.
Class 15. BASIDIO SPORE AE
The Basidium Fungi
374, The plants, or rather the fruits, of this class are
among the largest and most conspicuous of the fungi.
They are mostly saprophytes whose abundant vegetative
filaments {viycelium) ramify through the nourishing sub-
stance, and afterw^ard give rise to the conspicuous spore
fruits. The spores are produced usually in 4's upon
slender outgrowths from the ends of enlarged cells {ha-
sidia), the latter usually arranged parallel to each other
so as to form a spore-bearing surface Qiymenium) , which
may be external (as in Toadstools) or
internal (as in Puff-balls).
375. The basidia in this class are
here regarded as homologous wdth the
asci of the Ascosporeae. The differ-
ence between them is that in the asci
mento?''bI^Sia''a°nd the sporcs iu their development remain
basidiospores. inside of the ascus cavity, while in the
basidia the spores as they develop push out so as finally
to become external. It is obvious that the ascus is the
PUFF BALLS 227
more primitive structure, and that the basidium is a
hiter and a higher structure, probabl}^ derived from it.
376. There are about 14,000 species, which may be
separated into nine orders, and about twenty-five fami-
lies. A few only of these will be taken up here.
377. The lowest of the Basidium-fungi, the False
Tubers (Order Hymenogastrales) are subterranean
plants, with subterranean truffle-like, fleshy fruits, which
like the truffles are edible and wholesome. They are
distinguished from the truffles by the fact that they con-
tain basidia instead of asci.
378. The Pufif-balls (Order Lycoperdales). The
plants of this order are saprophj^tes, whose spore fruits
are often of large size, and usually more or less globular in
form. The basidiospores are always borne in the in-
terior of more or less regular cavities, and from these they
escape by the deliquescence, and subsequent drying and
rupture of the surrounding tissues.
379. The vegetative filaments of Puff-balls penetrate
the substance of decaying wood, and the soil filled with
decaying organic matter. They
usually aggregate themselves into
cylindrical root-like masses. After
an extended vegetative period the
filaments produce upon their root- fig. los.— Puff-haii and
like portions small rounded bodies, basidiospores.
the young spore fruits, which increase rapidly in size and
assume the forms characteristic of the different genera.
380. No sexual organs have yet been discovered, but
analogy points to their possible existence upon the vege-
tative filaments just previous to the first appearance of
the spore fruits. The spore fruits are composed of inter-
laced filaments loosely arranged in the interior, and an
external more compact limitary tissue forming a rind
228 PHYLUM VII. CARPOMYCETEAE
(peridium) . The basidia develop in a portion of the in-